Aptitude - Time and Work - Discussion

Discussion Forum : Time and Work - General Questions (Q.No. 4)
4.
A is thrice as good as workman as B and therefore is able to finish a job in 60 days less than B. Working together, they can do it in:
20 days
22 1 days
2
25 days
30 days
Answer: Option
Explanation:

Ratio of times taken by A and B = 1 : 3.

The time difference is (3 - 1) 2 days while B take 3 days and A takes 1 day.

If difference of time is 2 days, B takes 3 days.

If difference of time is 60 days, B takes 3 x 60 = 90 days.
2

So, A takes 30 days to do the work.

A's 1 day's work = 1
30

B's 1 day's work = 1
90

(A + B)'s 1 day's work = 1 + 1 = 4 = 2
30 90 90 45

A and B together can do the work in 45 = 22 1 days.
2 2

Discussion:
283 comments Page 29 of 29.

Ahamed said:   5 years ago
Thank you all for explaining.

Adheer said:   4 years ago
If B completes the work in X days, then A completes the work in X-60 days.

A is thrice good as workman as B then, the ratio of the time taken to finish the same work is 1:3
Then,

(X-60) : X :: 1 : 3

Solving this, X = 90
Means B finish the work in 90 days and A finishes the work in 30 Days,
Working together, their 1-day work,
1/90 + 1/30 = 4/90 = 2/45.
Mean working together, they finish the work in 45/2 = 22(1/2) days.

Srikanth said:   4 years ago
Thanks @Sundhar.


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